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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: rand.c,v 1.3 1999/12/10 23:28:07 mdw Exp $ |
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4 | * |
5 | * Secure random number generator |
6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: rand.c,v $ |
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33 | * Revision 1.3 1999/12/10 23:28:07 mdw |
34 | * Bug fix: rand_getgood didn't update buffer pointer. |
35 | * |
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36 | * Revision 1.2 1999/10/12 21:00:15 mdw |
37 | * Make pool and buffer sizes more sensible. |
38 | * |
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39 | * Revision 1.1 1999/09/03 08:41:12 mdw |
40 | * Initial import. |
41 | * |
42 | */ |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
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46 | #include <stdarg.h> |
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47 | #include <stdio.h> |
48 | #include <string.h> |
49 | |
50 | #include <mLib/bits.h> |
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51 | #include <mLib/sub.h> |
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52 | |
53 | #include "blowfish-cbc.h" |
54 | #include "paranoia.h" |
55 | #include "rand.h" |
56 | #include "rmd160.h" |
57 | #include "rmd160-hmac.h" |
58 | |
59 | /*----- Static variables --------------------------------------------------*/ |
60 | |
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61 | static const grand_ops gops; |
62 | |
63 | typedef struct gctx { |
64 | grand r; |
65 | rand_pool p; |
66 | } gctx; |
67 | |
68 | static gctx pool = { { &gops } }; /* Default random pool */ |
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69 | |
70 | /*----- Macros ------------------------------------------------------------*/ |
71 | |
72 | #define RAND_RESOLVE(r) do { \ |
73 | if ((r) == RAND_GLOBAL) \ |
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74 | (r) = &pool.p; \ |
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75 | } while (0) |
76 | |
77 | #define TIMER(r) do { \ |
78 | if ((r)->s && (r)->s->timer) \ |
79 | (r)->s->timer(r); \ |
80 | } while (0) |
81 | |
82 | /*----- Main code ---------------------------------------------------------*/ |
83 | |
84 | /* --- @rand_init@ --- * |
85 | * |
86 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
87 | * |
88 | * Returns: --- |
89 | * |
90 | * Use: Initializes a randomness pool. The pool doesn't start out |
91 | * very random: that's your job to sort out. |
92 | */ |
93 | |
94 | void rand_init(rand_pool *r) |
95 | { |
96 | RAND_RESOLVE(r); |
97 | memset(r->pool, 0, sizeof(r->pool)); |
98 | memset(r->buf, 0, sizeof(r->buf)); |
99 | r->i = 0; |
100 | r->irot = 0; |
101 | r->ibits = r->obits = 0; |
102 | r->o = RAND_SECSZ; |
103 | r->s = 0; |
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104 | rmd160_hmacinit(&r->k, 0, 0); |
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105 | rand_gate(r); |
106 | } |
107 | |
108 | /* --- @rand_noisesrc@ --- * |
109 | * |
110 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
111 | * @const rand_source *s@ = pointer to source definition |
112 | * |
113 | * Returns: --- |
114 | * |
115 | * Use: Sets a noise source for a randomness pool. When the pool's |
116 | * estimate of good random bits falls to zero, the @getnoise@ |
117 | * function is called, passing the pool handle as an argument. |
118 | * It is expected to increase the number of good bits by at |
119 | * least one, because it'll be called over and over again until |
120 | * there are enough bits to satisfy the caller. The @timer@ |
121 | * function is called frequently throughout the generator's |
122 | * operation. |
123 | */ |
124 | |
125 | void rand_noisesrc(rand_pool *r, const rand_source *s) |
126 | { |
127 | RAND_RESOLVE(r); |
128 | r->s = s; |
129 | } |
130 | |
131 | /* --- @rand_key@ --- * |
132 | * |
133 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
134 | * @const void *k@ = pointer to key data |
135 | * @size_t sz@ = size of key data |
136 | * |
137 | * Returns: --- |
138 | * |
139 | * Use: Sets the secret key for a randomness pool. The key is used |
140 | * when mixing in new random bits. |
141 | */ |
142 | |
143 | void rand_key(rand_pool *r, const void *k, size_t sz) |
144 | { |
145 | RAND_RESOLVE(r); |
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146 | rmd160_hmacinit(&r->k, k, sz); |
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147 | } |
148 | |
149 | /* --- @rand_add@ --- * |
150 | * |
151 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
152 | * @const void *p@ = pointer a buffer of data to add |
153 | * @size_t sz@ = size of the data buffer |
154 | * @unsigned goodbits@ = number of good bits estimated in buffer |
155 | * |
156 | * Returns: --- |
157 | * |
158 | * Use: Mixes the data in the buffer with the contents of the |
159 | * pool. The estimate of the number of good bits is added to |
160 | * the pool's own count. The mixing operation is not |
161 | * cryptographically strong. However, data in the input pool |
162 | * isn't output directly, only through the one-way gating |
163 | * operation, so that shouldn't matter. |
164 | */ |
165 | |
166 | void rand_add(rand_pool *r, const void *p, size_t sz, unsigned goodbits) |
167 | { |
168 | const octet *c = p; |
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169 | int i, rot; |
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170 | |
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171 | #if RAND_POOLSZ != 128 |
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172 | # error Polynomial in rand_add is out of date. Fix it. |
173 | #endif |
174 | |
175 | RAND_RESOLVE(r); |
176 | |
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177 | i = r->i; rot = r->irot; |
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178 | |
179 | while (sz) { |
180 | octet o = *c++; |
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181 | r->pool[i] ^= (ROL8(o, rot) ^ |
182 | r->pool[(i + 1) % RAND_POOLSZ] ^ |
183 | r->pool[(i + 2) % RAND_POOLSZ] ^ |
184 | r->pool[(i + 7) % RAND_POOLSZ]); |
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185 | rot = (rot + 5) & 7; |
186 | i++; if (i >= RAND_POOLSZ) i -= RAND_POOLSZ; |
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187 | sz--; |
188 | } |
189 | |
190 | r->i = i; |
191 | r->irot = rot; |
192 | r->ibits += goodbits; |
193 | if (r->ibits > RAND_IBITS) |
194 | r->ibits = RAND_IBITS; |
195 | } |
196 | |
197 | /* --- @rand_goodbits@ --- * |
198 | * |
199 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
200 | * |
201 | * Returns: Estimate of the number of good bits remaining in the pool. |
202 | */ |
203 | |
204 | unsigned rand_goodbits(rand_pool *r) |
205 | { |
206 | RAND_RESOLVE(r); |
207 | return (r->ibits + r->obits); |
208 | } |
209 | |
210 | /* --- @rand_gate@ --- * |
211 | * |
212 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
213 | * |
214 | * Returns: --- |
215 | * |
216 | * Use: Mixes up the entire state of the generator in a nonreversible |
217 | * way. |
218 | */ |
219 | |
220 | void rand_gate(rand_pool *r) |
221 | { |
222 | octet mac[RMD160_HASHSZ]; |
223 | |
224 | RAND_RESOLVE(r); |
225 | TIMER(r); |
226 | |
227 | /* --- Hash up all the data in the pool --- */ |
228 | |
229 | { |
230 | rmd160_macctx mc; |
231 | |
232 | rmd160_macinit(&mc, &r->k); |
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233 | rmd160_machash(&mc, r->pool, sizeof(r->pool)); |
234 | rmd160_machash(&mc, r->buf, sizeof(r->buf)); |
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235 | rmd160_macdone(&mc, mac); |
236 | BURN(mc); |
237 | } |
238 | |
239 | /* --- Now mangle all of the data based on the hash --- */ |
240 | |
241 | { |
242 | blowfish_cbcctx bc; |
243 | |
244 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
245 | blowfish_cbcencrypt(&bc, r->pool, r->pool, sizeof(r->pool)); |
246 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
247 | BURN(bc); |
248 | } |
249 | |
250 | /* --- Reset the various state variables --- */ |
251 | |
252 | r->o = RAND_SECSZ; |
253 | r->obits += r->ibits; |
254 | if (r->obits > RAND_OBITS) { |
255 | r->ibits = r->obits - r->ibits; |
256 | r->obits = RAND_OBITS; |
257 | } else |
258 | r->ibits = 0; |
259 | TIMER(r); |
260 | } |
261 | |
262 | /* --- @rand_stretch@ --- * |
263 | * |
264 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
265 | * |
266 | * Returns: --- |
267 | * |
268 | * Use: Stretches the contents of the output buffer by transforming |
269 | * it in a nonreversible way. This doesn't add any entropy |
270 | * worth speaking about, but it works well enough when the |
271 | * caller doesn't care about that sort of thing. |
272 | */ |
273 | |
274 | void rand_stretch(rand_pool *r) |
275 | { |
276 | octet mac[RMD160_HASHSZ]; |
277 | |
278 | RAND_RESOLVE(r); |
279 | TIMER(r); |
280 | |
281 | /* --- Hash up all the data in the buffer --- */ |
282 | |
283 | { |
284 | rmd160_macctx mc; |
285 | |
286 | rmd160_macinit(&mc, &r->k); |
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287 | rmd160_machash(&mc, r->pool, sizeof(r->pool)); |
288 | rmd160_machash(&mc, r->buf, sizeof(r->buf)); |
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289 | rmd160_macdone(&mc, mac); |
290 | BURN(mc); |
291 | } |
292 | |
293 | /* --- Now mangle the buffer based on that hash --- */ |
294 | |
295 | { |
296 | blowfish_cbcctx bc; |
297 | |
298 | blowfish_cbcinit(&bc, mac, sizeof(mac), 0); |
299 | blowfish_cbcencrypt(&bc, r->buf, r->buf, sizeof(r->buf)); |
300 | BURN(bc); |
301 | } |
302 | |
303 | /* --- Reset the various state variables --- */ |
304 | |
305 | r->o = RAND_SECSZ; |
306 | TIMER(r); |
307 | } |
308 | |
309 | /* --- @rand_get@ --- * |
310 | * |
311 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
312 | * @void *p@ = pointer to output buffer |
313 | * @size_t sz@ = size of output buffer |
314 | * |
315 | * Returns: --- |
316 | * |
317 | * Use: Gets random data from the pool. The pool's contents can't be |
318 | * determined from the output of this function; nor can the |
319 | * output data be determined from a knowledge of the data input |
320 | * to the pool wihtout also having knowledge of the secret key. |
321 | * The good bits counter is decremented, although no special |
322 | * action is taken if it reaches zero. |
323 | */ |
324 | |
325 | void rand_get(rand_pool *r, void *p, size_t sz) |
326 | { |
327 | octet *o = p; |
328 | |
329 | RAND_RESOLVE(r); |
330 | TIMER(r); |
331 | |
332 | if (!sz) |
333 | return; |
334 | for (;;) { |
335 | if (r->o + sz <= RAND_BUFSZ) { |
336 | memcpy(o, r->buf + r->o, sz); |
337 | r->o += sz; |
338 | break; |
339 | } else { |
340 | size_t chunk = RAND_BUFSZ - r->o; |
341 | if (chunk) { |
342 | memcpy(o, r->buf + r->o, chunk); |
343 | sz -= chunk; |
344 | o += chunk; |
345 | } |
346 | rand_stretch(r); |
347 | } |
348 | } |
349 | |
350 | if (r->obits > sz * 8) |
351 | r->obits -= sz * 8; |
352 | else |
353 | r->obits = 0; |
354 | } |
355 | |
356 | /* --- @rand_getgood@ --- * |
357 | * |
358 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
359 | * @void *p@ = pointer to output buffer |
360 | * @size_t sz@ = size of output buffer |
361 | * |
362 | * Returns: --- |
363 | * |
364 | * Use: Gets random data from the pool. The pool's contents can't be |
365 | * determined from the output of this function; nor can the |
366 | * output data be determined from a knowledge of the data input |
367 | * to the pool wihtout also having knowledge of the secret key. |
368 | * If a noise source is attached to the pool in question, it is |
369 | * called to replenish the supply of good bits in the pool; |
370 | * otherwise this call is equivalent to @rand_get@. |
371 | */ |
372 | |
373 | void rand_getgood(rand_pool *r, void *p, size_t sz) |
374 | { |
375 | octet *o = p; |
376 | |
377 | RAND_RESOLVE(r); |
378 | |
379 | if (!sz) |
380 | return; |
381 | if (!r->s || !r->s->getnoise) { |
382 | rand_get(r, p, sz); |
383 | return; |
384 | } |
385 | TIMER(r); |
386 | |
387 | while (sz) { |
388 | size_t chunk = sz; |
389 | |
390 | if (chunk * 8 > r->obits) { |
391 | if (chunk * 8 > r->ibits + r->obits) |
392 | do r->s->getnoise(r); while (r->ibits + r->obits < 128); |
393 | rand_gate(r); |
394 | if (chunk * 8 > r->obits) |
395 | chunk = r->obits / 8; |
396 | } |
397 | |
398 | if (chunk + r->o > RAND_BUFSZ) |
399 | chunk = RAND_BUFSZ - r->o; |
400 | |
401 | memcpy(o, r->buf + r->o, chunk); |
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402 | r->o += chunk; |
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403 | r->obits -= chunk * 8; |
404 | o += chunk; |
405 | sz -= chunk; |
406 | } |
407 | } |
408 | |
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409 | /*----- Generic random number generator interface -------------------------*/ |
410 | |
411 | static void gdestroy(grand *r) |
412 | { |
413 | gctx *g = (r == &rand_global ? &pool : (gctx *)r); |
414 | if (g != &pool) |
415 | DESTROY(g); |
416 | } |
417 | |
418 | static int gmisc(grand *r, unsigned op, ...) |
419 | { |
420 | gctx *g = (r == &rand_global ? &pool : (gctx *)r); |
421 | va_list ap; |
422 | int rc = 0; |
423 | va_start(ap, op); |
424 | |
425 | switch (op) { |
426 | case GRAND_CHECK: |
427 | switch (va_arg(ap, unsigned)) { |
428 | case GRAND_CHECK: |
429 | case GRAND_SEEDINT: |
430 | case GRAND_SEEDUINT32: |
431 | case GRAND_SEEDBLOCK: |
432 | case RAND_GATE: |
433 | case RAND_STRETCH: |
434 | case RAND_KEY: |
435 | case RAND_NOISESRC: |
436 | rc = 1; |
437 | break; |
438 | default: |
439 | rc = 0; |
440 | break; |
441 | } |
442 | break; |
443 | case GRAND_SEEDINT: { |
444 | unsigned u = va_arg(ap, unsigned); |
445 | rand_add(&g->p, &u, sizeof(u), sizeof(u)); |
446 | } break; |
447 | case GRAND_SEEDUINT32: { |
448 | uint32 i = va_arg(ap, uint32); |
449 | rand_add(&g->p, &i, sizeof(i), 4); |
450 | } break; |
451 | case GRAND_SEEDBLOCK: { |
452 | const void *p = va_arg(ap, const void *); |
453 | size_t sz = va_arg(ap, size_t); |
454 | rand_add(&g->p, p, sz, sz); |
455 | } break; |
456 | case RAND_GATE: |
457 | rand_gate(&g->p); |
458 | break; |
459 | case RAND_STRETCH: |
460 | rand_stretch(&g->p); |
461 | break; |
462 | case RAND_KEY: { |
463 | const void *k = va_arg(ap, const void *); |
464 | size_t sz = va_arg(ap, size_t); |
465 | rand_key(&g->p, k, sz); |
466 | } break; |
467 | case RAND_NOISESRC: |
468 | rand_noisesrc(&g->p, va_arg(ap, const rand_source *)); |
469 | break; |
470 | default: |
471 | GRAND_BADOP; |
472 | break; |
473 | } |
474 | |
475 | va_end(ap); |
476 | return (rc); |
477 | } |
478 | |
479 | static octet gbyte(grand *r) |
480 | { |
481 | gctx *g = (r == &rand_global ? &pool : (gctx *)r); |
482 | octet o; |
483 | rand_getgood(&g->p, &o, 1); |
484 | return (o); |
485 | } |
486 | |
487 | static uint32 gword(grand *r) |
488 | { |
489 | gctx *g = (r == &rand_global ? &pool : (gctx *)r); |
490 | octet b[4]; |
491 | rand_getgood(&g->p, &b, sizeof(b)); |
492 | return (LOAD32(b)); |
493 | } |
494 | |
495 | static void gfill(grand *r, void *p, size_t sz) |
496 | { |
497 | gctx *g = (r == &rand_global ? &pool : (gctx *)r); |
498 | rand_getgood(&g->p, p, sz); |
499 | } |
500 | |
501 | static const grand_ops gops = { |
502 | "rand", |
503 | 0, |
504 | gmisc, gdestroy, |
505 | gword, gbyte, gword, grand_range, gfill |
506 | }; |
507 | |
508 | grand rand_global = { &gops }; |
509 | |
510 | /* --- @rand_create@ --- * |
511 | * |
512 | * Arguments: --- |
513 | * |
514 | * Returns: Pointer to a generic generator. |
515 | * |
516 | * Use: Constructs a generic generator interface over a Catacomb |
517 | * entropy pool generator. |
518 | */ |
519 | |
520 | grand *rand_create(void) |
521 | { |
522 | gctx *g = CREATE(gctx); |
523 | g->r.ops = &gops; |
524 | rand_init(&g->p); |
525 | return (&g->r); |
526 | } |
527 | |
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528 | /*----- That's all, folks -------------------------------------------------*/ |